Many different types of electronic devices include an electronic visual display that can provide visual information to a user. For example, a liquid-crystal display (LCD) is a widely used type of display that can be found is a wide range of electronic devices, including digital cameras, watches, calculators, and mobile telephones, including smartphones. An LCD is a flat-panel display that is often a desirable display option for several reasons, which may include that LCDs are relatively thin, light-weight, and efficient in terms of power consumption. In addition, the LCDs are known to have high resolution, high color display, and high definition.
The LCD in most electronic devices is part of an LCD module that has an LCD panel and a built-in driving circuit unit. The LCD panel typically includes a thin-film transistor (TFT) array substrate, a color filter substrate, a liquid crystal layer located between the TFT array substrate and the color filter substrate, and a backlight assembly disposed under the LCD panel to serve as a light source. The driving circuit unit typically includes an LCD Driver Integrated Circuit (driver IC) disposed at an outer ring of the LCD panel to drive the LCD panel. The LCD panel includes pixels in a matrix shape between two glass substrates (the TFT array substrate and the color filter substrate mentioned above) with a switching device for controlling signals respectively supplied to the pixels, like a thin-film transistor. A plurality of pixels are disposed between the two glass substrates in a matrix pattern on the TFT array substrate. A switching element, such as a TFT, is provided for each pixel for controlling drive signals to the respective pixel.
The driving circuit unit includes the above-mentioned driver IC, as well as a printed circuit board (PCB) on which driving circuits are provided for generating various signals for driving the LCD panel, such as control signals, clock signals, and data signals. The driver IC is connected to the LCD panel and the PCB to apply a signal to the TFTs, storage capacitors, pixel electrodes, and interconnect wiring of the LCD panel. The interconnect wiring includes gate bus-lines and data bus-lines arranged so that each pixel is individually addressable by the driving circuit unit. The driver IC includes a set of bonding pads with each bonding pad including a metal bump. The surface to which the driver IC is to be mounted is provided with a matching set of pads. The driver IC is mounted on the surface by bonding the set of bonding pads to the matching set of pads.
Chip On Glass (COG) and Chip On Film (COF) are two common methods for mounting a driver IC and connecting it to control an LCD panel. COG is a flip-chip bonding technology where the driver IC is mounted to a non-display region of the LCD panel's array substrate using Anisotropic Conductive Film (ACF). COF is also a flip-chip bonding technology, but the driver IC is mounted to a flexible printed circuit board (FPC), which in turn is mounted to a non-display region of the LCD panel's array substrate. This is undesirable because it results in LCD modules and LCD panels that have an overall footprint that is larger than that the actual display and dead edge regions that get covered for aesthetic reasons in the final product (e.g., smartphone or tablet computer).
FIGS. 1 and 2 illustrate an example of the non-display region caused by installation of a driver IC using a COG arrangement. FIG. 1 shows a perspective view of a display module 100, which illustrates an example of COG technology. The display module 100 includes an LCD panel 102 and a driver region 104, which includes a driver IC 112 (shown in FIG. 2). The FPC 106 for outputting image signals from a data processing device to the driver region 104. More particularly, the LCD panel 102 includes a TFT array substrate 108, liquid crystal (not shown), and a color filter substrate 110.
The TFT array substrate 108 includes a liquid crystal controlling part that is disposed in an active display area. The liquid crystal controlling part includes TFTs and pixel electrodes that are electrically connected to driving lines that are driven by the driver IC 112.
The color filter substrate 110 is opposite to the active display area of the TFT substrate 108. The color filter substrate 110 includes a color filter (not shown) and a common electrode (not shown). The color filter substrate 110 is positioned near the pixel electrodes and covered with a common electrode.
The manufacturing process includes injecting liquid crystal into a gap between the TFT array substrate 108 and the color filter substrate 110, thereby producing the LCD panel 102.
FIG. 2 shows a partial side view of the portion of the display module 100 near the driver IC 112. The driver IC 112 is a source driving integrated circuit package mounted on data lines. The driver IC 112 receives image signals from some outside source via the image signal input bumps 114, converts the received image signals into corresponding drive signals (e.g., voltage or current signal), and transmits the drive signals to the LCD panel 102 via the driving signal output bumps 116.
The image signal input bumps 114 are connected to conductive patterns 118, which are in turn connected to the FPC 106 via an anisotropic conductive film (ACF) 120. The driving signal output bumps 116 are connected to data lines 122 via the anisotropic conductive film 120. The TFT array substrate 108 supports the conductive patterns 120 and data lines 122, as shown.
Thus, while the use of the display module 100 provides the convenience of an LCD panel 102 with an integrated driver IC 112 with COG technology, the array substrate 108 is made larger than the filter substrate 110 and active display area in order to provide space for the driver IC 112.
It would therefore be desirable to be able to provide improved packaging technologies and display modules that provide high levels of integration and reductions in display dead space. The present disclosure provides novel packaging technologies that include such desired improvements.